Fix for add_submenu_page notice

Notice: add_submenu_page was called incorrectly. The seventh parameter passed to add_submenu_page() should be an integer representing menu position.

On line 158 remove the seventh parameter

Reason: add_submenu_page does not take icon as any parameter

public function WMAMC_add_menulink() {

     $this->adminpage = add_submenu_page(
                'woocommerce',
                __('Add Cart Limit','wmamc-cart-limit'),
                __('Add Cart Limit','wmamc-cart-limit'), 
                'manage_woocommerce',
                'wmamc_cart_limit',
                array($this, 'WMAMC_render_submenu_pages' ),
                // 'dashicons-format-video' // <<< remove or comment this line
            );
}